P145 HCQ alleviates 5-FU-induced intestinal inflammation through inhibiting TLR9-dependent DNA sensing pathway

Career situation of first and presenting author Young investigator. Introduction Evidences revealed that chemotherapies could trigger DNA release, then induce inflammation of intestinal tissues which damp the effect of anti-cancer treatment. 1 2 DNA released induces the translocation of TLR9 to endolysosomes and subsequent nuclear factor-κB (NF-κB) activation, which leads to interleukin-1β (IL-1β) secretion and inflammation. 3 Targeting TLR9-dependent DNA sensing pathway may be a valuable therapy for chemotherapy induced intestinal mucositis. Objectives This study aims to investigate whether hydroxychloroquine (HCQ), suppresses 5-FU-induced intestinal mucositis through inhibiting TLR9-dependent DNA sensing pathway. Methods The effect of HCQ on 5-FU-induced intestinal mucositis were examined in vivo and in vitro . We established 5-FU-induced intestinal mucositis model and assessed body weight, diarrhea score and histopathologic changes following HCQ treatment in vivo , then TLR9 and NF-κB expression of small intestine and IL-1β secretion of serum were analyzed. Bone marrow-derived macrophages (BMDMs) were cultured, transfected with calf-thymus DNA(CT-DNA) and treated with HCQ for 6 hour in vitro . TLR9 and NF-κB expression and IL-1β secretion in BMDMs were then investigated. Results HCQ treatment markedly attenuated body weight loss, severity of diarrhea, intestine shortening, and destruction of small intestinal in histopathology of 5-FU- treated mice in vivo . Also HCQ treatment inhibited TLR9 and NF-κB expression in small intestine of 5-FU- treated mice and pro-inflammatory IL-1β secretion in serum of 5-FU- treated mice. Meanwhile administration of HCQ reduced the number of macrophages in small intestine of 5-FU-treated mice. Then BMDMs were cultured, transfected with CT-DNA and treated with HCQ in vitro . We found HCQ efficiently inhibited TLR9 expression, translocation of NF-κB to nucleus, and IL-1β secretion in supernatant of CT-DNA stimulated BMDMs. Conclusions These results provides a new insight into the mechanism of chemotherapy induced intestinal mucositis and indicate HCQ may be used as a strategy against intestinal mucositis during 5-FU chemotherapy. References Woo S-R, Fuertes MB, Corrales L, et al . STING-Dependent Cytosolic DNA Sensing Mediates Innate Immune Recognition of Immunogenic Tumors. Immunity 2014;41:830–42. Hu B, Jin C, Li H-B, et al . The DNA Sensing Aim2 Inflammasome Controls Radiation Induced Cell death and Tissue Injury. Science (New York, NY) . 2016;354:765–8. Miura K, Kodama Y, Inokuchi S, et al . Toll-Like Receptor 9 Promotes Steatohepatitis by Induction of Interleukin-1β in Mice. Gastroenterology . 2010;139:323–34.e7. Acknowledgements The authors confirm that there are no conflicts of interest. Disclosure of Interest None declared.